Method for producing plating composition

Abstract

Provided is a method for producing a plating composition that can be recovered from a plating composition containing metal ions in a high oxidation state. The method for producing a plating composition involves: in a working electrode chamber provided with a working electrode, using the working electrode as a cathode to reduce a portion of first metal ions contained in a first plating composition into metal, and thereby obtaining a reduction treatment liquid and a working electrode to which metal is adhered; bringing the reduction treatment liquid into contact with at least one type of adsorption material selected from the group consisting of chelate resins and ion exchange resins, and thereby obtaining a metal-ion-removed liquid from which at least some of the first metal ions have been further removed; and introducing the metal-ion-removed liquid into the working electrode chamber provided with the working electrode to which metal is adhered, using the working electrode to which metal is adhered as an anode to oxidize, in the metal-ion-removed liquid, at least a portion of the adhered metal into second metal ions having a lower oxidation number than the first metal ions, and thereby obtaining a second plating composition containing the second metal ions.

Description

Method for producing plating composition

[0001] The present invention relates to a method for producing a plating composition.

[0002] In relation to plating compositions used in metal plating, JP 2004-534151 A proposes a method for regenerating a plating solution in which electrolytically deposited tin is used to reduce tin(IV) ions to tin(II) ions. JP 2015-518923 A also proposes a method for regenerating a plating composition by oxidizing and reducing two types of metal components in the plating composition using an apparatus equipped with a working electrode chamber, a counter electrode chamber, and an ion exchange membrane separating them.

[0003] An object of one aspect of the present invention is to provide a method for producing a plating composition that can efficiently produce a plating composition that contains metal ions in a low oxidation state and that can be reused as a plating treatment solution from a plating composition that is derived from a used plating treatment solution and contains metal ions in a high oxidation state.

[0004] A first aspect of the present invention relates to a method for producing a plating composition, the method comprising the steps of: reducing a portion of the first metal ions contained in a first plating composition to metal in a working electrode chamber equipped with a working electrode, using the working electrode as a cathode, to obtain a reduction treatment solution and a working electrode having a metal attached thereto; contacting the reduction treatment solution with at least one adsorbent material selected from the group consisting of chelating resins and ion exchange resins to obtain a metal ion-removed solution from which at least a portion of the first metal ions have been further removed; and introducing the metal ion-removing solution into the working electrode chamber equipped with the working electrode having a metal attached thereto, and oxidizing at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions in the metal ion-removing solution, using the working electrode having a metal attached thereto as an anode, to obtain a second plating composition containing the second metal ions.

[0005] According to one aspect of the present invention, it is possible to provide a method for producing a plating composition that can efficiently produce a plating composition that contains metal ions in a low oxidation state and that can be reused as a plating treatment liquid from a plating composition that is derived from a used plating treatment liquid and contains metal ions in a high oxidation state.

[0006] 1 is a flowchart showing an example of the process sequence of a method for producing a plating composition; FIG. 2 is a flowchart showing an example of the process sequence of a method for producing a plating composition of another embodiment; and FIG. 3 is a schematic diagram illustrating an example of the process of a method for producing an electronic component.

[0007] As used herein, the term "process" refers not only to an independent process, but also to processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. Furthermore, when a composition contains multiple substances corresponding to each component, the term refers to the total amount of the multiple substances present in the composition, unless otherwise specified. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments described below are merely examples of methods for producing plating compositions to embody the technical concepts of the present invention, and the present invention is not limited to the methods for producing plating compositions described below.

[0008] 2. Method for Producing Plating Composition A method for producing a plating composition includes a first plating composition containing first metal ions, and includes the following steps: a first step of reducing a portion of the first metal ions contained in the first plating composition to metal in a working electrode chamber equipped with a working electrode, using the working electrode as a cathode, to obtain a reduced treatment solution and a working electrode having a metal attached thereto; a second step of contacting the reduced treatment solution with at least one adsorbent material selected from the group consisting of chelating resins and ion exchange resins to obtain a metal ion-removed solution from which at least a portion of the first metal ions have been further removed; and a third step of introducing the metal ion-removing solution into the working electrode chamber equipped with the working electrode having a metal attached thereto, and oxidizing at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions in the metal ion-removing solution, using the working electrode with the metal attached as an anode, to obtain a second plating composition containing the second metal ions.

[0009] The second plating composition obtained by contacting a reduction treatment solution from which a portion of the first metal ions has been removed with an adsorbent material capable of adsorbing the first metal ions and oxidizing and generating second metal ions in the metal ion-removed solution obtained by at least partially removing the first metal ions from the reduction treatment solution exhibits excellent plating quality when reused as a plating treatment solution. This is thought to be because, for example, the first metal ions contained in components that are contained in the reduction treatment solution and that may cause quality degradation in plating treatment are selectively adsorbed by the adsorbent material, while effective components such as complexing agents are efficiently recovered.

[0010] One embodiment of a method for producing a plating composition will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of the process sequence of the method for producing a plating composition. The method for producing a plating composition may include a first metal ion reduction step S101, a first metal ion adsorption step S102, and a second metal ion generation step S103. In the first metal ion reduction step (also referred to as step 1) S101, a first metal ion (e.g., tin(IV) ion) with a high oxidation state contained in the first plating composition is reduced to a metal (e.g., metallic tin) using an electrochemical device. The electrochemical device is configured by separating a working electrode chamber including a working electrode and a counter electrode chamber including a counter electrode by a diaphragm. The first metal ion is reduced by introducing the first plating composition into the working electrode chamber and applying current to the working electrode as a cathode. When the first metal ion is reduced, a metal is deposited on the working electrode, resulting in a working electrode with the metal attached and a reduction treatment solution in which a portion of the first metal ion has been removed from the first plating composition. In the first metal ion adsorption step S102 (also referred to as the second step), the reduction treatment solution is brought into contact with at least one adsorbent material selected from the group consisting of a chelating resin and an ion exchange resin, whereby the first metal ions contained in the reduction treatment solution are liberated from the complexing agent and the like and selectively adsorbed and removed. This selectively removes the first metal ions, yielding a metal ion-removed solution containing the remaining complexing agent and the like. In the second metal ion generation step S103 (also referred to as the third step), the metal ion-removing solution is introduced into a working electrode chamber equipped with a working electrode to which a metal has been attached. Using the working electrode to which the metal has been attached as the anode, at least a portion of the attached metal is oxidized in the metal ion-removing solution to second metal ions having a lower oxidation number than the first metal ions, thereby obtaining a second plating composition containing the second metal ions.

[0011] 2 is a flowchart showing an example of the process sequence of another embodiment of the plating composition manufacturing method. Another embodiment of the plating composition manufacturing method may include a surfactant removal step S201 in which at least a portion of the surfactant is removed from a plating wastewater recovered from a plating tank or a water-rinsing tank to obtain a first plating composition. Alternatively, after removing the surfactant, the first plating composition may be obtained by further removing a portion of the water in a concentration step S202, or the first plating composition may be obtained after the surfactant removal step S201 without going through the concentration step. Details of the surfactant removal step and the concentration step will be described later. From the obtained first plating composition, a second plating composition is obtained by a first metal ion reduction step S203, a first metal ion adsorption step S204, and a second metal ion generation step S205, as described above.

[0012] In yet another embodiment, the method for producing a plating composition may include removing a portion of water from a plating waste solution recovered from a plating tank or a water-rinsing tank in a concentration step, and then removing at least a portion of the surfactant in a surfactant removal step to obtain a first plating composition.

[0013] Furthermore, the concentration step may include a first concentration step in which a part of the water is removed from the plating waste liquid through a reverse osmosis membrane to obtain a first concentrated solution, and a second concentration step in which a part of the water is removed from the first concentrated solution under an inert gas atmosphere or a low-pressure environment to obtain a second concentrated solution.

[0014] First Step In the first step, first metal ions contained in the first plating composition are reduced using a working electrode of an electrochemical device as the cathode to obtain an elemental metal resulting from the reduction of the first metal ions. The elemental metal may be deposited on the working electrode, for example, to form a metal-adhered working electrode. The first step may be performed using an electrochemical device including a working electrode chamber having a working electrode and a counter electrode chamber having a counter electrode, the working electrode chamber and the counter electrode chamber being separated by a diaphragm. The diaphragm may be one selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane. The first plating composition is introduced into the working electrode chamber of the electrochemical device. An aqueous solution containing conductive ions may be placed in the counter electrode chamber of the electrochemical device. Placing the aqueous solution containing conductive ions in the counter electrode chamber allows for more efficient reduction of the first metal ions.

[0015] The first plating composition may be, for example, a plating wastewater used in metal plating, or a plating wastewater obtained by rinsing a metal-plated article with water.

[0016] The first metal ions contained in the first plating composition may be metal ions in a more highly oxidized state than the second metal ions, and may be generated by oxidation of the second metal ions constituting the plating composition before use. Examples of the first metal ions include tin(IV) ions, Cu(II) ions, and Fe(III) ions. The first metal ions may include at least tin(IV) ions.

[0017] The content of the first metal ion in the first plating composition may be, for example, 0.1 g / L or more and 100 g / L or less, and preferably 1 g / L or more. The first plating composition may also contain a complexing agent, and the content thereof may be, for example, equimolar to 20 times the molar amount of the first metal ion, and preferably 10 times or less. The content of the complexing agent in the first plating composition may be, for example, 0.2 mol / L or more and 2.5 mol / L or less, and preferably 0.5 mol / L or more or 1.0 mol / L or less. The content of the first metal ion in the first plating composition is measured, for example, by inductively coupled plasma atomic emission spectroscopy (ICP-AES) or by a combination of oxidation-reduction titration with potassium iodate after reduction with iron powder and oxidation-reduction titration with iodine or iodate.

[0018] Examples of materials for the working electrode provided in the working electrode chamber include gold, platinum, platinum-coated titanium, silver, nickel, graphite, tin, titanium, iridium oxide, and ruthenium oxide. Examples of materials for the counter electrode include platinum, platinum-coated titanium, gold, nickel, iridium oxide, ruthenium oxide, titanium, graphite, and palladium. The working electrode chamber and the counter electrode chamber are separated, for example, by an ion exchange membrane. This allows for more efficient reduction of the first metal ion. The ion exchange membrane may be a cation exchange membrane, an anion exchange membrane, or a combination of both. The ion exchange membrane may be appropriately selected from commercially available ion exchange membranes. The ion exchange membrane may include at least a cation exchange membrane from the viewpoint of the reduction efficiency of the first metal ion. For example, the cation exchange membrane may include a fluororesin copolymer based on sulfonated tetrafluoroethylene. In addition, instead of the ion exchange membrane, a membrane that is difficult for the first metal ions to permeate, such as a reverse osmosis membrane (RO membrane) or a nanofiltration membrane (NF membrane, loose RO membrane), may be used.

[0019] When a conductive ion-containing aqueous solution is placed in the counter electrode chamber, the conductive ion-containing aqueous solution may contain at least water and conductive ions. The conductive ions may be derived from a water-soluble metal salt or a water-soluble acidic compound (acid component). Examples of conductive ions include cations such as hydrogen ions, alkali metal ions, and alkaline earth metal ions; and anions such as sulfate ions, nitrate ions, phosphate ions, halogen ions, alkylsulfonate ions, alkanolsulfonate ions, aromatic sulfonate ions, alkylcarboxylate ions, and aromatic carboxylate ions. The alkyl group constituting the anion may have, for example, 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. The aromatic group may be an aryl group or a heteroaryl group, and the aromatic group may have, for example, 4 to 10 carbon atoms, preferably 6 carbon atoms. Examples of heteroatoms in the heteroaryl group include nitrogen atoms, oxygen atoms, and sulfur atoms. The alkyl group and aromatic group may have at least one substituent, such as a halogen atom, an aliphatic group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms.

[0020] In the first step, a portion of the first metal ions in the first plating composition introduced into the working electrode chamber are reduced to elemental metals by a first electrolysis treatment using the first working electrode as a cathode. The elemental metals produced by the reduction may, for example, be deposited and adhered to the first working electrode. The current density in the electrolysis treatment of the first metal ions may be appropriately selected depending on the type of first metal ions. The current density is, for example, 0.05 A / dm ２ 10A / dm or more ２ may be less than or equal to 0.1 A / dm ２ or more, or 7 A / dm ２ The temperature in the electrolysis treatment may be, for example, 20° C. or higher and 80° C. or lower, and preferably 35° C. or higher or 75° C. or lower. The time required for the electrolysis treatment may be, for example, 10 minutes or longer and 200 hours or shorter.

[0021] The first metal ion contained in the first plating composition may be a simple metal ion or a complex ion. Examples of complexing agents that form complex ions include carboxylic acids, such as gluconic acid (including gluconolactone), citric acid, glutaric acid, succinic acid, malic acid, tartaric acid, lactic acid, acetic acid, malonic acid, and salts or derivatives thereof; phosphoric acids, such as tripolyphosphoric acid and hydroxyethanediphosphonic acid, and salts thereof; sugars, such as sorbitol, mannitol, and salts thereof; amino acids, such as phenylalanine, glutamic acid, aspartic acid, alanine, glycine, and salts thereof; HEDTA, EDTA, and the like. The complexing agent may contain at least one selected from the group consisting of these, and may contain at least gluconic acid. The complexing agents may be used alone or in combination of two or more. By forming a complex ion with the first metal ion, it becomes possible to set the pH of the plating composition used for plating to a weakly acidic to weakly alkaline range, thereby suppressing corrosion of the object to be plated that is vulnerable to strong acids or strong alkalis (e.g., an object that uses an oxide as a component, such as a ceramic capacitor).

[0022] The first plating composition may contain, in addition to the first metal ion, a second metal ion having a lower oxidation number than the first metal ion. A specific example of the second metal ion is a tin(II) ion when the first metal ion is a tin(IV) ion. A specific example of the second metal ion is an Fe(II) ion when the first metal ion is an Fe(III) ion. The second metal ion may be a simple metal ion or a complex ion. The complexing agent that forms the complex ion is the same as that for the first metal ion. When the first plating composition contains the second metal ion, the content of the second metal ion contained in the first plating composition may be, for example, 100 g / L or less, preferably 20 g / L or less. The content of the second metal ion contained in the first plating composition is measured by oxidation-reduction titration using iodine or iodate.

[0023] The total content of the first metal ions and the second metal ions in the first plating composition may be, for example, 0.1 g / L or more and 100 g / L or less, preferably 1 g / L or more, 5 g / L or more, or 10 g / L or more, and preferably 70 g / L or less, or 50 g / L or less.

[0024] The second metal ions may be derived from the plating composition prior to use. The second metal ions constituting the plating composition prior to use may be derived from a water-soluble metal salt. Specific examples of water-soluble metal salts include sulfates, chlorides, boron fluorides, alkanesulfonates, alkanolsulfonates, aromatic sulfonates, and sulfamates. The plating composition may contain at least one selected from the group consisting of these, and may contain at least an alkane sulfonate. Examples of the alkane sulfonic acid in the alkane sulfonate include alkanesulfonic acids having 1 to 3 carbon atoms, and specific examples include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and 2-propanesulfonic acid.

[0025] The first plating composition may further contain alkali metal ions, alkaline earth metal ions, ammonium ions, etc., derived from the plating composition prior to use. The inclusion of a conductive agent such as alkali metal ions, alkaline earth metal ions, or ammonium ions increases conductivity, suppresses heat generation due to solution resistance during electroplating, and tends to improve electrodeposition uniformity. Examples of alkali metal ions include lithium ions, sodium ions, potassium ions, rubidium, and cesium ions. Examples of alkaline earth metal ions include calcium ions, strontium ions, and barium ions. The alkali metal ions, alkaline earth metal ions, and ammonium ions may be added to the plating composition prior to use as salts with, for example, an acid component. The inclusion of an acid component in the plating composition prior to use, for example, further improves the stability of the plating composition. The acid component may also be included in the plating composition as a conductive agent. Examples of acid components include sulfuric acid, hydrochloric acid, alkylsulfonic acid, alkanolsulfonic acid, aromatic sulfonic acid, phosphoric acid, alkylcarboxylic acid, aromatic carboxylic acid, and sulfamic acid, and the plating composition may contain at least one selected from the group consisting of these. These acid components may be used alone or in combination of two or more.

[0026] The pH of the first plating composition may be, for example, 0 or more and 14 or less, preferably 0.5 or more, 3 or more, or 4 or more, and preferably 11 or less, 9 or less, or 7 or less. When the pH of the first plating composition is within the above range, the first metal ions tend to be reduced more efficiently. The pH of the first plating composition may be adjusted to a desired range, for example, with a pH adjuster. Examples of pH adjusters include the acid components described above as well as alkaline components such as alkali metal hydroxides and ammonia.

[0027] The first plating composition may further contain an antioxidant derived from the plating composition prior to use. The inclusion of an antioxidant can, for example, improve the stability of the plating composition prior to use and extend the bath life. Examples of antioxidants include hydroquinone, ascorbic acid, catechol, hypophosphorous acid, and erythorbic acid. When the first plating composition contains an antioxidant, the content of the antioxidant in the first plating composition may be, for example, 0.01 g / L or more and 20 g / L or less, and preferably 0.1 g / L or more or 5 g / L or less.

[0028] If the first plating composition includes an antioxidant, the first step may include removing at least a portion of the antioxidant, which may be accomplished by, for example, activated carbon treatment.

[0029] The first plating composition contains water as a solvent. The total concentration of solutes in the first plating composition may be, for example, 750 g / L or less, preferably 400 g / L or less, or 300 g / L or less. The total concentration of solutes in the first plating composition may be, for example, 50 g / L or more.

[0030] The first plating composition may contain a surfactant derived from the plating composition prior to use. The surfactant may be any of a nonionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, etc. Furthermore, the surfactant may function as a so-called brightener, leveler, etc. in the plating composition. From the viewpoint of the reduction efficiency of the first metal ion, the surfactant may contain at least one surfactant selected from the group consisting of a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. The first plating composition may contain only one surfactant, or a combination of two or more surfactants.

[0031] Examples of nonionic surfactants include ester surfactants in which a polyhydric alcohol such as glycerin, sorbitol, or sucrose is ester-bonded to a fatty acid; ether surfactants formed by adding ethylene oxide, propylene oxide, or the like to a compound having a hydroxyl group such as a higher alcohol or an alkylphenol; and ester-ether surfactants formed by adding ethylene oxide, propylene oxide, or the like to an ester surfactant. Specific examples of nonionic surfactants include polyethylene glycol, polypropylene glycol, polyoxyethylene octylphenol, polyoxyethylene β-naphthyl ether, polyoxyethylene alkylamine, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid ester and its ethylene oxide adduct, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid monoethanolamide and its ethylene oxide adduct, fatty acid N-methyl monoethanolamide and its ethylene oxide adduct, fatty acid diethanolamide and its ethylene oxide adduct, sucrose fatty acid ester, alkyl (poly)glycerin ether, polyglycerin fatty acid ester, polyethylene glycol fatty acid ester, fatty acid methyl ester ethoxylate, N-long-chain alkyldimethylamine oxide, etc. Nonionic surfactants may have fluorine atoms substituted in their structures.

[0032] Examples of cationic surfactants include amine salts and quaternary ammonium salts.Specific examples of cationic surfactants include alkyl (or alkenyl) trimethyl ammonium salts, alkyl (or alkenyl) triethyl ammonium salts, dialkyl (or alkenyl) dimethyl ammonium salts, alkyl (or alkenyl) quaternary ammonium salts, mono- or dialkyl (or alkenyl) quaternary ammonium salts containing ether groups, ester groups, or amide groups, alkyl (or alkenyl) pyridinium salts, alkyl (or alkenyl) dimethyl benzyl ammonium salts, alkyl (or alkenyl) isoquinolinium salts, dialkyl (or alkenyl) morphonium salts, polyoxyethylene alkyl (or alkenyl) amines, alkyl (or alkenyl) amine salts, polyamine fatty acid derivatives, amyl alcohol fatty acid derivatives, benzalkonium chloride, benzethonium chloride, etc.These cationic surfactants may have fluorine atoms substituted in their structures.

[0033] Amphoteric surfactants exhibit the properties of anionic surfactants in the alkaline range and the properties of cationic surfactants in the acidic range. Examples of amphoteric surfactants include carboxylates and sulfonates, and may be either amino acid-type or betaine-type. Specific examples of amphoteric surfactants include alkyldimethylaminoacetic acid betaine, alkyldimethylacetic acid betaine, alkyldimethylcarboxybetaine, alkyldimethylcarboxymethyleneammonium betaine, alkyldimethylammonioacetate, fatty acid amidopropyldimethylamino acid betaine, alkyloylamidopropyldimethylglycine, 2-alkyl-1-(2-hydroxyethyl)imidazolium-1-acetate, alkyldiaminoethylglycine, dialkyldiaminoethylglycine, and alkyldimethylamine oxide.

[0034] Examples of the anionic surfactant include carboxylates, sulfonates, sulfates, and phosphates.

[0035] The surfactant content in the first plating composition may be, for example, 0.01 g / L or more and 10 g / L or less, and preferably 0.1 g / L or more or 5 g / L or less. The surfactant content can be measured using surface tension as an index. Specifically, it can be measured using a drop counter, a surface tensiometer, or the like.

[0036] When the first plating composition contains a surfactant, a surfactant removal step of removing at least a portion of the surfactant from the first plating composition may be carried out prior to the first step. This allows the reduction of the first metal ions to be carried out more efficiently. The surfactant content in the first plating composition after removal in the surfactant removal step may be, for example, 0.01 g / L or less.

[0037] Examples of methods for removing the surfactant in the surfactant removal step include activated carbon treatment and gel filtration treatment. The surfactant removal method may preferably include activated carbon treatment. The surfactant removal method using activated carbon treatment may include, for example, contacting the first plating composition with activated carbon. By using activated carbon, at least a portion of the surfactant can be more efficiently removed from the first plating composition. In the surfactant removal step, a method of electrostatically adsorbing the surfactant (e.g., contacting the surfactant with an ion exchange resin) may be combined with activated carbon treatment.

[0038] Activated carbon is a porous material whose main component is carbon and that has been subjected to a chemical or physical activation process. The activated carbon used in the activated carbon process may be activated with chemicals or gases. The activated carbon may be powdered activated carbon, granular activated carbon, or a combination of these.

[0039] The specific surface area of ​​activated carbon is, for example, 200 m ２ / g or more 1500m ２ / g or less, and preferably 300m ２ / g or more, or 700m ２ / g or less. The specific surface area is measured based on the BET (Brunauer Emmett Teller) theory using nitrogen gas after heat treatment at 200°C for 6 hours as a pretreatment. The average pore diameter of the activated carbon may be, for example, 1.5 nm or more and 3.5 nm or less, and preferably 2.0 nm or more and 3.0 nm or less. The mesopore shape of the activated carbon may be, for example, an average pore width on the adsorption side measured by the INNES method of 2 nm or more and 30 nm or less, and preferably 4 nm or more and 10 nm or less. The average pore width on the desorption side measured by the INNES method may be, for example, 2 nm or more and 5 nm or less, and preferably 2 nm or more and 3.5 nm or less.

[0040] The amount of activated carbon used in contact with the first plating composition may be selected appropriately depending on the type of activated carbon. The amount of activated carbon used may be an amount sufficient to remove at least a portion of the surfactant contained in the first plating composition, preferably an amount sufficient to remove 50% by mass or more, 70% by mass or more, or 90% by mass or more of the surfactant. The amount of activated carbon used may be selected depending on the method of contact with the first plating composition. For example, when contacting in a single pass, a larger amount of activated carbon may be required than when contacting by circulating the first plating composition.

[0041] The first plating composition may be contacted with the activated carbon by, for example, mixing the first plating composition with the activated carbon followed by solid-liquid separation, or by passing the plating composition through activated carbon held in a filter, cartridge, etc. The contact temperature between the first plating composition and the activated carbon may be, for example, 0°C or higher or 70°C or lower.

[0042] In one embodiment, the method for producing a plating composition may further include a concentration step in which a portion of the water is removed from the plating wastewater to obtain a first plating composition. Performing the first step using the concentrated first plating composition allows for more efficient removal of the first metal ions. The plating wastewater subjected to the concentration step may be one from which at least a portion of the surfactant has been removed in the surfactant removal step, or may be a plating wastewater from which the surfactant has not been removed. Preferably, the plating wastewater may be one from which at least a portion of the surfactant has been removed. From the viewpoint of concentration efficiency, the concentration step may include a first concentration step in which a portion of the water is removed through a reverse osmosis membrane (hereinafter also referred to as an RO membrane) to obtain a first concentrated solution, and a second concentration step in which a portion of the water is removed from the first concentrated solution under an inert gas atmosphere or a low-pressure environment to obtain a second concentrated solution.

[0043] In the first concentration step, a first concentrated solution is obtained by removing a portion of the water from a plating wastewater containing first metal ions and water through a reverse osmosis membrane. Generally, when concentrating a plating wastewater containing oxidizable metal ions by removing a portion of the water, the lower the metal ion concentration and the higher the temperature, the more likely the oxidation of the metal ions will proceed. By using a reverse osmosis membrane to concentrate the plating wastewater, it is possible to rapidly concentrate a large amount of plating wastewater while suppressing the oxidation of the metal ions.

[0044] A reverse osmosis membrane is a type of filtration membrane that allows water molecules to pass through but blocks substances other than water molecules, such as ions. A reverse osmosis membrane separates a solution A with a high salt concentration (e.g., a first plating composition) from a solution B with a low salt concentration (e.g., water). When a pressure greater than the difference in osmotic pressure between solutions A and B is applied to the side of solution A with a high salt concentration, only water molecules move from solution A to solution B. This allows a portion of the water to be removed from the plating wastewater to obtain a first concentrated solution, and water can also be obtained as reverse osmosis membrane-treated water.

[0045] Examples of materials for the reverse osmosis membrane include polyamide, polysulfone, cellulose acetate, etc., and preferably include polyamides including aromatic polyamides or crosslinked aromatic polyamides. For concentrating the plating wastewater using a reverse osmosis membrane, for example, a tubular module or a spiral module equipped with a reverse osmosis membrane can be used.

[0046] The liquid feed pressure when concentrating plating wastewater using a reverse osmosis membrane may be appropriately selected depending on the type of reverse osmosis membrane used. The liquid feed pressure during concentration may be, for example, 0.5 MPa or more, preferably 1 MPa or more, or 2 MPa or more. The liquid feed pressure may be, for example, 10 MPa or less. The temperature during concentration may be, for example, 0°C or more and 50°C or less, preferably 10°C or more and 40°C or less.

[0047] The ratio (concentration factor) of the volume of the plating waste solution to the volume of the first concentrated solution from which part of the water has been removed via the reverse osmosis membrane may be, for example, 2 or more, and preferably 3 or more.

[0048] In the second concentration step, a portion of the water is removed from the first concentrated liquid under an inert gas atmosphere or a low-pressure environment to obtain a second concentrated liquid. By removing a portion of the water from the first concentrated liquid under an inert gas atmosphere or a low-pressure environment, it is possible to obtain a second concentrated liquid from which a portion of the water has been further removed while effectively suppressing oxidation of metal ions contained in the first concentrated liquid.

[0049] Examples of the inert gas in the inert gas atmosphere in the second concentration step include rare gases such as argon, nitrogen gas, etc. The concentration of the inert gas in the inert gas atmosphere may be, for example, 80% by volume or more, preferably 90% by volume or more, or 95% by volume or more. The pressure in the inert gas atmosphere may be normal pressure or may be reduced below atmospheric pressure. The inert gas atmosphere under reduced pressure may be substituted with an inert gas and then reduced, or an inert gas atmosphere may be created by supplying an inert gas when adjusting the degree of vacuum.

[0050] The low-pressure environment in the second concentration step may be an environment under reduced pressure lower than atmospheric pressure, and specifically, the pressure in the low-pressure environment may be, for example, 50 hPa or less, preferably 10 hPa or less, or 1 hPa or less.

[0051] In one embodiment, the second concentration step may be a step of removing a portion of water from the first concentrate in a low-oxygen environment to obtain the second concentrate. The low-oxygen environment may have an oxygen concentration of, for example, 2% by volume or less, preferably 1% by volume or less, or 0.5% by volume or less.

[0052] Examples of methods for removing water in the second concentration step include a first concentration method in which a portion of the water is removed from the first concentrated liquid under reduced pressure, a second concentration method in which the first concentrated liquid is frozen and then a portion of the water is removed from the frozen first concentrated liquid under reduced pressure, and a third concentration method in which a mist containing water is generated from the first concentrated liquid under an inert gas atmosphere or under reduced pressure and at least a portion of the generated mist is removed.

[0053] In the first concentration method, a portion of the water is removed from the first concentrated liquid under reduced pressure. The degree of vacuum in the first concentration method can be, for example, 500 hPa or less, preferably 200 hPa or less, or 100 hPa or less. The degree of vacuum may be, for example, 1 hPa or more, or 100 hPa or more. In the first concentration method, a portion of the water may be removed while heating the first concentrated liquid under reduced pressure. When the first concentrated liquid is heated, the temperature may be, for example, 30°C or more and 80°C or less, preferably 35°C or more or 40°C or more, and preferably 70°C or less or 60°C or less. In the first concentration method, the first concentrated liquid may be stirred. The stirring method can be appropriately selected from commonly used stirring methods. Examples of stirring methods include a method of rotating a container containing the first concentrated liquid to stir, a method of stirring the first concentrated liquid in a container using a rotor or the like, and a method of pouring the first concentrated liquid into a container while spraying it. In the first concentration method, the atmosphere inside the container can be replaced with an inert gas before reducing the pressure, thereby removing part of the water under an inert gas atmosphere.

[0054] The second concentration method includes freezing the first concentrated liquid and removing a portion of the water from the frozen first concentrated liquid under reduced pressure. The freezing of the first concentrated liquid can be performed by lowering the liquid temperature of the first concentrated liquid to, for example, −15°C or lower, preferably −25°C or lower. It is preferable to replace the atmosphere inside the container with an inert gas during freezing. In the second concentration method, the container containing the frozen first concentrated liquid is depressurized, and a portion of the water contained in the first concentrated liquid is removed by freeze-drying, which sublimes the solid state. The degree of vacuum in the second concentration method may be, for example, 10 hPa or lower, preferably 1 hPa or lower. The second concentration method can be performed, for example, using a freeze dryer. According to the second concentration method, water can be removed at low temperatures under highly reduced pressure, thereby more effectively suppressing oxidation of metal ions. In the second concentration method, a portion of the water can be removed under an inert gas atmosphere by replacing the atmosphere inside the container with an inert gas before depressurizing.

[0055] The third concentration method involves generating a mist containing water from the first concentrated liquid (hereinafter also referred to as "atomization") and removing at least a portion of the generated mist. One method for generating a mist containing water from the first concentrated liquid is ultrasonic atomization, in which ultrasonic vibrations are applied to the first concentrated liquid. Ultrasonic atomization is a phenomenon in which ultrasonic vibrations are applied to a liquid, generating a fountain-like liquid column on the liquid surface, and fine droplets (mist), mainly measuring several microns, are generated from the sides of the liquid column. By atomizing the liquid without heating it, ultrasonic atomization can separate substances at the molecular cluster level. Separation of substances by ultrasonic atomization is possible, for example, by utilizing the fact that molecules of the same substance tend to cluster in liquid and the fact that clusters vary in size depending on the substance. The third concentration method can be performed, for example, using an atomization separation device (e.g., manufactured by NanoMist Technologies, Inc.).

[0056] Specifically, a portion of the water can be removed from the first concentrated liquid as follows. Ultrasonic vibrations are applied to the first concentrated liquid to generate a mist consisting of water clusters and a mist containing water and other components contained in the first concentrated liquid. The generated mist is separated using a classification device such as a cyclone, with the "light mist" consisting of water clusters rising and the "heavy mist" containing components other than water falling. The light mist, water, is liquefied by condensation through cooling or other means and removed from the first concentrated liquid. Meanwhile, the heavy mist can be recovered by allowing it to fall under its own weight and liquefy. In the third concentration method, ultrasonic atomization is performed in an inert gas atmosphere, and an inert gas is used in the airflow used in the cyclone, thereby removing a portion of the water in an inert gas atmosphere. According to the third concentration method, a portion of the water can be removed in an inert gas atmosphere without heating the first concentrated liquid, thereby more effectively suppressing the oxidation of metal ions.

[0057] In the third concentration method, ultrasonic atomization may be performed while heating the first concentrated liquid. When ultrasonic atomization is performed while heating, the liquid temperature of the first concentrated liquid may be, for example, 20°C or higher and 80°C or lower, preferably 20°C or higher or 30°C or higher, and preferably 70°C or lower.

[0058] The total concentration of solutes in the second concentrate obtained by removing a portion of the water from the first concentrate may be, for example, 30 g / L or more, preferably 50 g / L or more, or 80 g / L or more. The total concentration of solutes in the second concentrate may be, for example, 500 g / L or less. In the second concentration step, the ratio of the volume of the first concentrate to the volume of the second concentrate (concentration factor) may be, for example, 2 or more and 20 or less, preferably 3 or more or 10 or less. By controlling the concentration factor of the first concentrate in the second concentration step within the above range, the first metal ions can be reduced more efficiently in the first step.

[0059] The reduction treatment solution obtained in the first step may contain first metal ions and water, and may further contain a complexing agent capable of forming a metal complex with the first metal ions. The reduction treatment solution may further contain second metal ions in addition to the first metal ions. The total content of the first metal ions and the second metal ions in the reduction treatment solution may be, for example, 1 g / L or more and 20 g / L or less, and preferably 2 g / L or more or 10 g / L or less. The content of the complexing agent in the reduction treatment solution may be, for example, 0.2 mol / L or more and 2.5 mol / L or less, and preferably 0.5 mol / L or more or 1.0 mol / L or less.

[0060] The reduction treatment solution may further contain a conductive agent such as an acid component and cations, such as alkali metal ions, alkaline earth metal ions, and ammonium ions, derived from the first plating composition. Details of the cations, acid components, and the like are as described above. The content of the specific cations, including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, in the reduction treatment solution may be, for example, 0.2 mol / L or more and 2.5 mol / L or less, and preferably 0.5 mol / L or more or 1.5 mol / L or less. Furthermore, the content of the acid component in the reduction treatment solution may be, for example, 0.2 mol / L or more and 2.5 mol / L or less, and preferably 0.5 mol / L or more or 1.5 mol / L or less.

[0061] Step 2: In step 2, at least one adsorbent material selected from the group consisting of chelating resins and ion exchange resins is contacted with the reduction-treatment solution obtained in step 1 to remove at least a portion of the first metal ions contained in the reduction-treatment solution, thereby obtaining a metal-ion-removed solution. The reduction-treatment solution is believed to contain first metal ions that exist in a state that is difficult to reduce by electrolytic reduction (e.g., a specific metal complex). In general, in metal complexes, the metal ions and complexing agents are in equilibrium. Therefore, when the adsorbent material selectively removes the first metal ions, the equilibrium is shifted, resulting in further liberation of the first metal ions from the metal complex. Because the adsorbent material can selectively adsorb the first metal ions, contacting the reduction-treatment solution with the adsorbent material removes the first metal ions, thereby sufficiently reducing the content of complexes containing the first metal ions that may affect plating quality. Meanwhile, components other than the first metal ions, such as complexing agents, are not removed by the adsorbent material and remain in the metal-ion-removed solution. This makes it possible to efficiently recover components other than the first metal ions, such as complexing agents, and improve the plating quality when the second plating composition produced using the metal ion removal solution is used as a plating treatment solution.

[0062] The adsorbent material is not particularly limited as long as it is capable of adsorbing the first metal ion. Here, "adsorbable" means that the first metal ion can be localized on the adsorbent material due to an interaction between the functional group of the adsorbent material and the first metal ion. Examples of interactions between the functional group of the adsorbent material and the first metal ion include ionic bonds, coordinate bonds, hydrogen bonds, and the like, and combinations of these may also be used. Furthermore, the adsorbent material may adsorb the first metal ion by forming a chelate between the functional group of the adsorbent material and the first metal ion, or by forming an ionic bond between the functional group of the adsorbent material and the first metal ion. From the viewpoint of selectivity for the first metal ion, the adsorbent material may include at least one type of chelating resin.

[0063] The chelating resin may be a resin having a functional group capable of forming a chelate with the first metal ion. Examples of compounds from which the functional group capable of forming a chelate is derived include iminodiacetic acid, polyamines (e.g., aliphatic polyamines), alkyl sulfides, alkyl or aryl sulfonic acids, alkyl or aryl amines, alkyl or aryl phosphonic acids, N-methylglucamine, aminophosphoric acid, amidoxime, bispicolylamine, thiourea, and semithiocarbamic acid. When the first metal ion is a tin(IV) ion, the chelating resin may be a resin containing a functional group derived from at least one selected from the group consisting of N-methylglucamine, aminophosphoric acid, iminodiacetic acid, and polyamines. Examples of resins that serve as the base material for the chelating resin include cellulose, polystyrene resins, and styrene-divinylbenzene copolymers. The adsorption material may contain only one type of chelating resin, or a combination of two or more types.

[0064] A specific example of a chelating resin is Chelest Fiber. （Ｒ） GRY-HW, Chelest Fiber （Ｒ） GRY-H (all manufactured by Cherest), DIAION （ＴＭ） CRB03, CRB05 (both manufactured by Mitsubishi Chemical Corporation), Duolite （ＴＭ） Chelate resins having functional groups derived from N-methylglucamine, such as ES371N (manufactured by Sumika Chemtex Co., Ltd.); Muromac XMS-5416 (manufactured by Muromachi Chemical Co., Ltd.), AMBERSEP IRC747UPS (manufactured by Organo Corporation), and Duolite （ＴＭ） Examples include chelating resins having functional groups derived from aminophosphoric acid, such as C467 (manufactured by Sumika Chemtex Co., Ltd.).

[0065] The ion exchange resin may be a resin having a functional group capable of forming an ionic bond with the first metal ion. Examples of the functional group capable of forming an ionic bond, i.e., a salt, with the first metal ion include a sulfonic acid group and a carboxyl group. The adsorption material may contain only one type of ion exchange resin or a combination of two or more types.

[0066] Specific examples of ion exchange resins include DIAION （ＴＭ） SK1B (Mitsubishi Chemical), IR120B (Organo), Duolite （ＴＭ） C20 (manufactured by Sumika Chemtex Co., Ltd.) and the like.

[0067] The contact between the reduction treatment liquid and the adsorbent material may be carried out by a batch method or a column method. The contact between the reduction treatment liquid and the adsorbent material in the batch method can be carried out, for example, by mixing the reduction treatment liquid and the adsorbent material and stirring as necessary. After the contact between the reduction treatment liquid and the adsorbent material in the batch method, the adsorbent material is removed from the reduction treatment liquid by solid-liquid separation (e.g., filtration) to obtain a treated metal ion-removed liquid. The contact between the reduction treatment liquid and the adsorbent material in the column method can be carried out, for example, by passing the reduction treatment liquid through a column packed with the adsorbent material. The number of times the reduction treatment liquid is passed through the column may be, for example, from 1 to 100 times, preferably from 10 to 50 times. In the column method, the treated metal ion-removed liquid can be obtained as the effluent from the column. When the reduction treatment liquid is continuously passed through the column, one pass is considered to have been passed when a volume of liquid equivalent to the total volume of the reduction treatment liquid has been passed through.

[0068] The contact temperature between the reduction treatment solution and the adsorption material may be, for example, 20° C. or higher and 30° C. or lower, and preferably 22° C. or higher or 28° C. or lower. In the case of a batch method, the contact time between the reduction treatment solution and the adsorption material may be, for example, 1 hour or higher and 48 hours or lower, and preferably 2 hours or higher or 24 hours or lower. In the case of a column method, the contact time may be, for example, 1 hour or higher and 5 hours or lower, and preferably 2 hours or higher.

[0069] In the metal ion-removed liquid obtained by contacting the reduction-treated liquid with the adsorbent material, at least a portion of the first metal ions have been removed from the reduction-treated liquid. The ratio of the content of the first metal ions contained in the metal ion-removed liquid to the content of the first metal ions contained in the reduction-treated liquid may be, for example, 0.1 or less, preferably 0.05 or less, or 0.03 or less. That is, the removal rate of the first metal ions contained in the reduction-treated liquid by the adsorbent material may be, for example, 90% or more, preferably 95% or more, or 97% or more. Here, the content of the first metal ions in the reduction-treated liquid and the metal ion-removed liquid can be measured by oxidation-reduction titration or inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0070] The metal ion-removing solution may contain a complexing agent derived from the reduction treatment solution. The ratio of the content of the complexing agent contained in the metal ion-removing solution to the content of the complexing agent contained in the reduction treatment solution may be, for example, 0.75 or more, preferably 0.8 or more, or 0.9 or more. That is, the transmittance of the complexing agent contained in the reduction treatment solution through the adsorbent material may be, for example, 75% or more, preferably 80% or more, or 90% or more. Note that the content of the complexing agent in the reduction treatment solution and the metal ion-removing solution refers to the content of free complexing agent that has not formed a metal complex. Here, the content of the complexing agent in the reduction treatment solution and the metal ion-removing solution can be measured by titration.

[0071] The metal ion-removing solution may contain cations such as alkali metal ions, alkaline earth metal ions, and ammonium ions, and a conductive agent such as an acid component. When the metal ion-removing solution contains specific cations including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, the ratio of the content of the specific cations contained in the metal ion-removing solution to the content of the specific cations contained in the reduction treatment solution may be, for example, 0.75 or more, preferably 0.8 or more, or 0.9 or more. That is, the transmittance of the specific cations contained in the reduction treatment solution through the adsorbent material may be, for example, 75% or more, preferably 80% or more, or 90% or more. When the metal ion-removing solution contains an acid component, the ratio of the content of the acid component contained in the metal ion-removing solution to the content of the acid component contained in the reduction treatment solution may be, for example, 0.75 or more, preferably 0.8 or more, or 0.9 or more. That is, the transmittance of the adsorbent material to the acid component contained in the reduction treatment solution may be, for example, 75% or more, preferably 80% or more, or 90% or more. Here, the content of the specific cation in the reduction treatment solution and the metal ion-removed solution can be measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the content of the acid component can be measured by capillary electrophoresis (CE).

[0072] The method for producing a plating composition may further include a regeneration step of removing at least a portion of the first metal ions from the adsorbent material used in the second step to regenerate the adsorbent material.

[0073] In the third step, a metal ion-removing solution is introduced into a working electrode chamber equipped with a working electrode having a metal attached thereto, and in the metal ion-removing solution, the working electrode having the metal attached thereto is used as an anode to oxidize at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions, thereby obtaining a second plating composition containing the second metal ions. In the third step, in addition to the attached metal, a portion of the metal constituting the working electrode may also be oxidized to the metal ions.

[0074] By using a metal ion removal solution from which at least a portion of the first metal ions have been selectively removed to oxidize the metal attached to the working electrode to second metal ions and prepare a second plating composition, it is possible to achieve excellent plating quality when used in a plating process.

[0075] The oxidation of the metal attached to the working electrode to the second metal ions is carried out by electrolysis in a metal ion removal solution introduced into the working electrode chamber, with the working electrode to which the metal is attached serving as the anode. The current density in the electrolysis of the metal may be selected appropriately depending on the type of metal. The current density is, for example, 0.5 A / dm ２ More than 100A / dm ２ The temperature during electrolysis of the metal may be, for example, 10° C. or higher and 80° C. or lower, and preferably 15° C. or higher or 75° C. or lower. The time required for electrolysis may be, for example, 0.2 hours or higher and 10 hours or lower.

[0076] The method for producing a plating composition may further include a step of adding a surfactant to the second plating composition obtained in the third step. Plating using a plating composition containing a surfactant results in a plating having a better surface. The surfactant added may be the same type as the surfactant removed in the surfactant removal step described above. The amount of surfactant added may be approximately the same as the amount of surfactant removed in the surfactant removal step.

[0077] The method for producing a plating composition according to this embodiment may be used in combination with a plating method or a method for producing electronic components that includes a plating step. By using the method for producing a plating composition in combination, it is possible to suppress discharge of plating wastewater in the plating method or the method for producing electronic components.

[0078] Plating Method The plating method includes a plating composition production step and a plating step of contacting an object to be plated with a plating solution containing at least a portion of the plating composition obtained in the production step to form a plating layer on the surface of the object to be plated. The plating composition production step is the same as the plating composition production method described above. By using a plating solution containing the plating composition obtained by the plating composition production method described above, a plating layer of excellent quality equivalent to that formed when a plating solution prepared immediately before use is used can be formed on the object to be plated.

[0079] In the plating process, a plating solution is brought into contact with an object to be plated to form a plating layer on the surface of the object to be plated. The plating layer may be, for example, a tin plating layer. The plating process may be electrolytic plating or electroless plating, preferably electrolytic plating. The plating solution may be a commonly used tin plating solution, except that it contains at least a portion of the regenerated plating composition obtained in the regeneration process. The plating solution may be composed of, for example, tin (II) ions, a surfactant, a complexing agent, etc. In addition to the regenerated plating composition, the plating solution may further contain, as necessary, the surfactant, etc. removed in the regeneration process.

[0080] There are no particular limitations on the object to be plated to which the plating method is applied, as long as it is an article on whose surface a plating layer can be formed, such as a ceramic body having a conductive layer on its surface, a composite body containing a resin and a metal magnetic powder, a substrate, an electrode provided on a base material, etc.

[0081] The thickness of the plating layer formed in the plating step is not particularly limited and may be appropriately selected depending on the purpose, etc. The thickness of the plating layer may be, for example, 0.01 μm to 100 μm, preferably 0.1 μm to 50 μm, more preferably 0.3 μm to 10 μm, for example, 0.3 μm to 3 μm or 1 μm to 5 μm.

[0082] In the plating step, a known plating method can be applied, such as barrel plating, centrifugal plating, rack plating, or the like.

[0083] 2. Method for Manufacturing Electronic Components The method for manufacturing electronic components includes a plating composition manufacturing step and an electrode formation step of contacting a substrate having a conductive layer on its surface with a plating solution containing at least a portion of the plating composition obtained in the manufacturing step, to form an electrode layer containing a plating layer on the surface of the conductive layer. The plating composition manufacturing step is the same as the method for manufacturing the plating composition described above. By using a plating solution containing the recycled plating composition obtained by the method for manufacturing the plating composition described above, it is possible to form external electrodes containing electrode layers of excellent quality equivalent to those obtained by using a plating solution prepared just before use, and it is possible to manufacture highly reliable electronic components.

[0084] For details of electronic components manufactured by the manufacturing method for electronic components, see, for example, JP 2021-027195 A, WO 2023 / 171394, WO 2020 / 218218 (the disclosures of these documents are incorporated herein by reference in their entirety).

[0085] In the electrode formation step, a plating solution is brought into contact with an element having a conductive layer on its surface to form an electrode layer including a plating layer. The plating method in the electrode formation step may be electrolytic plating or electroless plating, preferably electrolytic plating. The plating solution may be a commonly used plating solution except that it contains at least a portion of the plating composition obtained in the plating composition production step. The plating solution may be composed of, for example, tin (II) ions, a surfactant, a complexing agent, etc. In addition to the produced plating composition, the plating solution may further contain, as necessary, surfactants and the like removed in the production step.

[0086] The element body subjected to the electrode formation step may be a component body of an electronic component. The component body is not particularly limited, and may be, for example, a multilayer ceramic capacitor, an inductor, a resistor, an LC composite component, a thermistor, or the like. In one embodiment, the component body may be a multilayer ceramic capacitor. The component body may be constructed using a method commonly used depending on the type of component body. The material of the component body is not particularly limited, and may be a material commonly used depending on the type of component body. Examples of materials include ceramic, resin, metal, and composites thereof. In one embodiment, the material of the component body may be ceramic.

[0087] The thickness of the plating layer included in the electrode layer formed in the electrode formation step is not particularly limited and may be appropriately selected depending on the purpose, etc. The thickness of the electrode layer may be, for example, 0.01 μm to 100 μm, preferably 0.1 μm to 50 μm, more preferably 0.3 μm to 10 μm, for example, 0.3 μm to 3 μm or 1 μm to 5 μm.

[0088] In the electrode formation step, a known plating method can be applied, such as barrel plating, centrifugal plating, rack plating, or the like.

[0089] An example of steps included in a method for manufacturing an electronic component will be described with reference to the drawings. FIG. 3 is a schematic diagram showing a portion of the steps of a method for manufacturing an electronic component according to one embodiment of the present invention. In this method, element bodies having a conductive layer on their surfaces are introduced into a tin plating tank 10 by an introduction means 12, and an electrode layer including a tin plating layer is formed on the conductive layer of the element bodies introduced into the tin plating tank 10. Water evaporates 16 from the tin plating tank 10. Next, the element bodies with the electrode layer formed thereon are pumped out of the tin plating tank by an extraction means 14 into a rinsing tank 20. For example, a countercurrent multistage rinsing tank is used as the rinsing tank 20. The element bodies are pumped downstream of the countercurrent multistage rinsing tank and move upstream. The element bodies with the electrode layer formed thereon are separated from the countercurrent multistage rinsing tank in the most upstream tank by a separation means 24. The element bodies with the separated electrode layer formed thereon are subjected to a drying process. In the countercurrent multistage rinsing tank 20, water is supplied from the upstream side by a water supply means 22, and the rinsing water moves downstream. The rinsing water (first plating composition) 26 taken out from the most downstream tank is introduced into a plating composition manufacturing apparatus 30.

[0090] In the plating composition manufacturing apparatus 30, at least a portion of the surfactant is removed from the tin-containing wash water using a surfactant removal means 32 that uses activated carbon. A first concentrator 36 using a reverse osmosis membrane removes a portion of the water from the wash water, thereby obtaining a first concentrate. The water 36a removed from the wash water is supplied to the wash tank 20 as reclaimed water 26. The first concentrate, from which a portion of the water has been removed via the reverse osmosis membrane, is further subjected to a second concentrator 37 under an inert gas atmosphere or a low-pressure environment to obtain a second concentrate. The water 37a removed from the second concentrate is supplied to the wash tank 20 as reclaimed water 26, together with the water 36a removed from the wash water. The second concentrate is introduced into an electrochemical device 34 that includes a working electrode chamber and a counter electrode chamber separated by a membrane. The second concentrate may contain tin(IV) ions as the first metal ions and may further contain tin(II) ions as the second metal ions. In the electrochemical device 34, a portion of the tin(IV) ions in the wash water is reduced to metallic tin in the first working electrode chamber 34a, using the working electrode as the cathode. This results in a working electrode with metallic tin attached to its surface and a reduced-treatment solution from which some of the tin(IV) ions have been removed. Furthermore, if the second concentrated solution contains tin(II) ions, at least some of the tin(II) ions in the second concentrated solution may be reduced to metallic tin using the working electrode as the cathode. The reduced-treatment solution is then subjected to adsorption and removal of at least some of the tin(IV) ions by an adsorption means 35 containing at least one adsorption material selected from the group consisting of a chelating resin and an ion exchange resin, thereby obtaining a metal-ion-removed solution. The metal-ion-removed solution obtained from the adsorption means 35 is then introduced into the second working electrode chamber 34b. In the second working electrode chamber 34b, an electrolysis process is performed using the working electrode with the tin metal attached as an anode, whereby at least a portion of the reduced tin metal is oxidized to tin(II) ions to produce a second plating composition 38 that can be reused in plating processes. Additives such as surfactants are added to the produced second plating composition 36 as needed, and the resulting composition is introduced into the tin plating tank 10 for reuse.According to one aspect of this embodiment, tin-containing wash water, which has conventionally been discarded, can be reused as a regenerated plating composition, thereby contributing to a reduction in waste.

[0091] The invention according to the present disclosure may include, for example, the following aspects: [1] A method for producing a plating composition, comprising: in a working electrode chamber including a first plating composition containing first metal ions, reducing a portion of the first metal ions contained in the first plating composition to metal using the working electrode as a cathode, to obtain a reduction treatment solution and a working electrode having the metal attached thereto; bringing the reduction treatment solution into contact with at least one adsorbent material selected from the group consisting of a chelating resin and an ion exchange resin, to obtain a metal ion-removed solution from which at least a portion of the first metal ions have been further removed; and introducing the metal ion-removing solution into a working electrode chamber including the working electrode having the metal attached thereto, and oxidizing at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions in the metal ion-removing solution, using the working electrode having the metal attached as an anode, to obtain a second plating composition containing the second metal ions.

[0092] [2] The manufacturing method according to [1], wherein the ratio of the content of the first metal ions in the metal ion removal solution to the content of the first metal ions in the reduction treatment solution is 0.1 or less.

[0093] [3] The manufacturing method according to [1] or [2], wherein the first plating composition further contains a complexing agent.

[0094] [4] The manufacturing method according to [3], wherein the ratio of the content of the complexing agent in the metal ion-removing solution to the content of the complexing agent in the reduction treatment solution is 0.75 or more.

[0095] [5] The manufacturing method according to any one of [1] to [4], wherein the first metal ion is a tetravalent tin ion and the second metal ion is a divalent tin ion.

[0096] [6] The manufacturing method according to [5], wherein the adsorption material comprises a resin having a functional group derived from at least one selected from the group consisting of N-methylglucamine, aminophosphate, iminodiacetic acid, and polyamine.

[0097] [7] The manufacturing method according to [5] or [6], wherein the first plating composition has a total tin ion content of 5 g / L or more and 70 g / L or less.

[0098] [8] The manufacturing method according to any one of [5] to [7], wherein the reduction treatment solution has a total tin ion content of 1 g / L or more and 10 g / L or less.

[0099] [9] The manufacturing method according to any one of [1] to [8], wherein the first plating composition further contains a specific cation including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, and an acid component.

[0100]

[10] The manufacturing method according to [9], wherein the reduction treatment solution has a content of the specific cation of 0.2 mol / L or more and 2.5 mol / L or less, and a content of the acid component of 0.2 mol / L or more and 2.5 mol / L or less.

[0101]

[11] The manufacturing method according to [9] or

[10] , wherein the ratio of the content of specific cations in the metal ion removal solution to the content of specific cations in the reduction treatment solution is 0.75 or more, and the ratio of the content of acid components in the reduction treatment solution to the content of acid components in the reduction treatment solution is 0.75 or more.

[0102]

[12] The manufacturing method according to any one of [1] to

[11] , further comprising removing at least a portion of a surfactant from a plating waste solution derived from a plating solution used in a plating treatment to obtain the first plating composition.

[0103]

[13] The manufacturing method according to any one of [1] to

[12] , further comprising removing at least a portion of water from a plating waste solution derived from a plating solution used in a plating treatment to obtain the first plating composition.

[0104] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0105] Example 1 Preparation of Plating Composition 1 Plating Composition 1 having the composition shown below was prepared using purified water, tin(II) methanesulfonate as a tin(II) ion source, gluconic acid, and sodium methanesulfonate, and by appropriately aerating the mixture, some of the tin(II) ions were oxidized to tin(IV) ions.

[0106] Composition: Tin (IV) ions: 0.16 mol / L, Tin (II) ions: 0.04 mol / L, Complexing agent: Gluconic acid: 0.8 mol / L, Conductive agent: Methanesulfonic acid: 1.2 mol / L, Cation: Sodium ions: 1.4 mol / L

[0107] The plating composition 1 prepared above was introduced into the working electrode chamber of an electrochemical device. The electrochemical device had a platinum-coated titanium electrode as the working electrode and a platinum-coated titanium electrode as the counter electrode, and the working electrode chamber and the counter electrode chamber were separated by a cation exchange membrane (Noafion （ＴＭ） The electrolysis device was placed in a counter electrode chamber with a 10 g / L aqueous solution of sodium sulfate, and the working electrode was set as the cathode. The temperature of the solution was between 40 and 70°C, and the current was 0.1 A / dm ２ to 5.0 A / dm ２ The electrolytic reduction treatment was carried out for 16 hours at a current density of 1000 kJ / min, to obtain a reduction treatment solution.

[0108] The resulting reduction treatment solution was immersed in a chelating resin (DIAION manufactured by Mitsubishi Chemical Corporation) having a functional group derived from N-methylglucamine. （ＴＭ） CRB05) at room temperature (25°C) to obtain a metal ion-removed solution.

[0109] The obtained metal ion-removed solution was introduced into the working electrode chamber of an electrochemical device, and the working electrode was used as the anode, and the solution temperature was set to 20°C to 70°C and the current was 1 A / dm ２ to 80 A / dm ２ The electrolytic oxidation treatment was carried out at a current density of 1000 ppm for 0.5 hours to obtain a second plating composition.

[0110] The content of each component in the resulting reduction treatment solution, metal ion removal solution, and second plating composition was quantified. The results are shown in Table 1. The content of each component was quantified using inductively coupled plasma atomic emission spectroscopy (ICP-AES), redox titration, or capillary electrophoresis (CE).

[0111]

[0112] Example 2 Preparation of Plating Composition 2 Plating composition 2 having the following composition was prepared in the same manner as in Example 1.

[0113] Composition: Tin (IV) ions: 0.16 mol / L, Tin (II) ions: 0.04 mol / L, Complexing agent: Gluconic acid: 0.8 mol / L, Conductive agent: Methanesulfonic acid: 1.2 mol / L, Surfactant: 1.0 g / L, Hydroquinone: 1.0 g / L, Cation: Sodium ions: 1.4 mol / L

[0114] The plating composition prepared above was passed through an activated carbon cartridge (MX, manufactured by Kankyo Technos Co., Ltd.) attached to a filter at room temperature (25°C) to obtain a first plating composition. Except for using the obtained first plating composition, electrolytic reduction treatment, metal ion removal, and electrolytic oxidation treatment were carried out in the same manner as in Example 1. The contents of each component in the obtained reduction treatment solution, metal ion removal solution, and second plating composition were quantified. The results are shown in Table 2.

[0115]

[0116] By performing a plating process using the second plating composition obtained above, a plating layer of excellent quality equivalent to that obtained when a plating solution prepared freshly for use is formed on the object to be plated.

[0117] The disclosure of Japanese Patent Application No. 2024-088205 (filing date: May 30, 2024) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A method for producing a plating composition, comprising: in a working electrode chamber containing a first plating composition containing first metal ions, reducing a portion of the first metal ions contained in the first plating composition to metal using the working electrode as a cathode, to obtain a reduction treatment solution and a working electrode having the metal attached; bringing the reduction treatment solution into contact with at least one adsorbent material selected from the group consisting of chelating resins and ion exchange resins, to obtain a metal ion-removed solution from which at least a portion of the first metal ions are further removed; and introducing the metal ion-removing solution into a working electrode chamber containing the working electrode having the metal attached, and oxidizing at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions in the metal ion-removing solution, using the working electrode having the metal attached as an anode, to obtain a second plating composition containing the second metal ions.

2. The manufacturing method according to claim 1, wherein the ratio of the content of the first metal ions in the metal ion removal solution to the content of the first metal ions in the reduction treatment solution is 0.1 or less.

3. The manufacturing method according to claim 1 or 2, wherein the first plating composition further comprises a complexing agent.

4. The manufacturing method according to claim 3, wherein the ratio of the content of the complexing agent in the metal ion removal solution to the content of the complexing agent in the reduction treatment solution is 0.75 or more.

5. The manufacturing method according to any one of claims 1 to 4, wherein the first metal ion is a tetravalent tin ion and the second metal ion is a divalent tin ion.

6. The method of claim 5, wherein the adsorption material comprises a resin having a functional group derived from at least one selected from the group consisting of N-methylglucamine, aminophosphate, iminodiacetic acid, and polyamine.

7. The manufacturing method according to claim 5 or 6, wherein the first plating composition has a total tin ion content of 5 g / L or more and 70 g / L or less.

8. A manufacturing method according to any one of claims 5 to 7, wherein the reduction treatment solution has a total tin ion content of 1 g / L or more and 10 g / L or less.

9. A manufacturing method described in any one of claims 1 to 8, wherein the first plating composition further contains a specific cation including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, and an acid component.

10. The manufacturing method described in claim 9, wherein the reduction treatment solution has a content of the specific cation of 0.2 mol / L or more and 2.5 mol / L or less, and a content of the acid component of 0.2 mol / L or more and 2.5 mol / L or less.

11. A manufacturing method described in claim 9 or 10, wherein the ratio of the content of specific cations contained in the metal ion removal solution to the content of specific cations contained in the reduction treatment solution is 0.75 or more, and the ratio of the content of acid components contained in the reduction treatment solution to the content of acid components contained in the reduction treatment solution is 0.75 or more.

12. A manufacturing method according to any one of claims 1 to 11, further comprising removing at least a portion of the surfactant from a plating waste solution derived from a plating solution used in a plating process to obtain the first plating composition.

13. The manufacturing method according to any one of claims 1 to 12, further comprising removing at least a portion of water from a plating waste solution derived from a plating solution used in a plating process to obtain the first plating composition.

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